Study On Disease Mechanism And Control Measures Of Subgrade Bed Diseases For Existing Railway

:The subgrade diseases of existing railway line not only severely weakened normal use, but also a direct threat to the safe operation. So how to evaluate efficiently the impact of the subgrade diseases, exploring a safe, low-cost, fast and effective reinforcement measure has great practical significance. Two common diseases (mud pumping and settlement of subgrade) engineering design and repairing effect have been systematic studied by using field investigation, mechanism analysis, scheme comparison and effect verification in subgrade reinforcement engineering, and a relatively complete construction technique scheme for the comprehensive regulating works of subgrade diseases is offered. The research results can be a useful reference in theory and method for the similar subgrade diseases of existing railway line, as follows.(1) Based on a large qualities of data analysis and experiments investigation and filed experiments, we summarize and gain that the major types of subgrade diseases in the supporting engineering are mud pumping and settlement of subgrade and the subgrade with inadequate bearing capacity. The geology, subgrade filling selection, track bed pollution, track bed ply inadequacy, drainage layout unreasonable, construction quality, old railroad line reform and line maintenance are the major factors that cause subgrade diseases.(2) Considering influence factors of the dynamic load of train, FLAC-3D software is used to simulate the response problem of typical subgrade on existing railway line under the dynamic load of trains after choosing the appropriate model. Analysis indicates that the ride performance on railway track is in a poor condition. The affecting depth, the settlement and the outward horizontal displacement of subgrade filling increased with the increase of the dynamic load of train, and the higher the subgrade filling, the severer the disease.(3) Considering the practical engineering, using valuable and successful experiences for reference, comparing the results between before and after the reinforcement by numerical methods, six regulation schemes have been designed, then based on this, the comprehensive regulating works of subgrade diseases on existing railway line is obtained.(4) Combining with the supporting engineering, a targeted, regional and appropriate a technique scheme for the comprehensive regulating works of subgrade diseases has been put forward. After the comparison of the results between before and after the reinforcement, the reinforcement method of the track bed, as suggested in this article, has a positive effect to improve subgrade strength.